Originally Posted by MaadMaxx
You can't really compare Zed's dash with Gragas or Graves. Zeds is so so much more useless then theirs. Gragas's is on a MUCH shorter cd and deals dmg and slows movement in an AOE, and graves gives him bonus AS and passively resets the cd for every shot fired. All in all their dashes actually make sense as part of their kit. Zed's dash does not.
Obviously Riot doesn't agree with you, else they'd have given him a different people. And give his dash a chance, many people thought Elise's spider E was rubbish when she first came out because all it does is give you 2 seconds of untargetable then drop you at an enemy with a massive CD, but anyone who is still playing Elise seriously will tell you now that her spider E is a major asset. Human E is still sh!t though but you can't have everything.
As to the dash CD, it is high for an important reason which is that his burst damage potential is significantly reduced when it is on cooldown; an important feature of an assassin. If the CD on his dash was shorter then his damage output would be too consistant for anybody to cope with. Assassin damage is meant to be powerful but sporadic; they all have a skill with a significantly longer cooldown and it often involves mobility, like LeBlanc's W or Katarina's E.
As for the high damage on his other abilities, people have to keep in mind that he doesn't get to spam his ult like many other assassins. Akali's ult works off charges, Katarina's passive typically lowers the CD of hers (and refreshes with 3 kills), Diana can use hers twice and then again within 25 seconds, and LB can use hers nearly three times a minute at max rank, more with CDR. Zed on the other hand has an 80 second wait without CDR, leaving his damage output otherwise deficient for over a minute when his ult is on cooldown.
On the other hand base damage on abilities at low rank can be an issue on champions who don't use mana, where their potential for harrassing is unlimited. I personally feel that his skills hit too hard at low levels, especially considering the missile speed on that Q makes it supremely difficult to dodge. It doesn't take long for a Zed to harrass someone down with his Q at no significant cost to himself; no mana, minimal effort, and low risk because of its decent range. It does 75 base damage at Rank 1 to the first target, with slightly lower output on subsequent targets, which can be kept up indefinately while most other champions are in the area of 80 for single target damage that quickly drains mana.
So there may or may not still be problems with Zed's balance, but his dash CD and end game Q damage are not significant parts of that.